Peter Ko Seong-dae, also called ‘Yeobin`, was born in Byeolam, Deoksan, Chungcheong-do (now, Sangjang-ri, Godeok-myeon, Yesan-gun, Chungnam). He learned about the catechism from his parents when he was a little boy and became a Catholic. By nature he had a violent temper and people avoided him. But when he practiced his religion with zeal his temperament changed gradually.

He was a dutiful son to his parents. When his father was sick in bed for eight months he prayed fervently, with his younger brother Joseph Ko Seong-un, for the recovery of his father`s health. The two brothers read the Bible together and meditated on it, and earnestly exhorted people to believe in God. In this way they became a good example to other believers.

Peter Ko moved to Jeokuri, Gosan (now, Jeoko-ri, Unju-myeon, Wanju-gun, Jeonbuk). He was arrested by the police of Jeonju during the Shinyu Persecution of 1801. At first he professed his faith courageously. The severe torture tempted him to save his own life. He betrayed his religion, and was set free.

But on returning home, Peter Ko immediately repented his mistake. He often said to himself; "I really do deserve decapitation to compensate for my enormous sin." Then he moved to Noraesan, Cheongsong (now, Norae 2-dong, Andeok-myeon, Cheongsong-gun, Gyeongbuk) with his younger brother. He led a relatively peaceful life with the believers of that village.

On Easter Sunday in 1815, while they were celebrating the Solemnity of the Resurrection of Christ, he and his brother Joseph and all the other Catholics of the village were arrested by the police who raided their place of worship accompanied by an informer and were taken to Gyeongju. It was around February 22.

During the interrogation and cruel torture Peter Ko remained firm in his faith. Then the chief official of Gyeongju sent the two brothers and other Catholics who refused to apostatize to Daegu, which was ruled by the governor. In Daegu they underwent severe interrogations and torture. They were imprisoned for more than seventeen months.

Peter Ko endured all these hardships and remained constant in professing his faith. He and his younger brother Joseph Ko were condemned to death. On December 19, 1816 (November 1, by the Lunar calendar) they were beheaded and died martyrs. He was single and celibate.

Prior to their martyrdom, the governor of Daegu, who noticed that the two brothers remained firm in their faith despite severe punishment, reported to the royal court as follows:

"The two brothers, Ko Seong-dae and Ko Seong-un, steeped in Catholicism, are so foolish and ignorant that they never realized their wrong-doing. I tried to help them to understand their wrong-doing in believing in the Catholic religion, but they never changed their minds. I cannot forgive their sins because they obstinately persist in keeping their resolution to die for their faith."

After they were martyred, the bodies of Peter Ko and Joseph Ko were buried near the execution ground. Then on March 2 of the following year, relatives and believers reburied them in an appropriate place.